Large-scale translocation reversal within the thylakoid Tat system in vivo
UNSPECIFIED. (2005) Large-scale translocation reversal within the thylakoid Tat system in vivo. JOURNAL OF CELL BIOLOGY, 171 (2). pp. 281-289. ISSN 0021-9525Full text not available from this repository.
In vitro import assays have shown that the thylakoid twin- arginine translocase (Tat) system transports folded proteins in a unidirectional manner. Here, we expressed a natural substrate, pre-23K, and a 23K presequence green fluorescent protein (GFP) chimera in vivo in tobacco protoplasts. Both are imported into chloroplasts, targeted to the thylakoids, and processed to the mature size by the lumen-facing processing peptidase. However, the vast majority of mature GFP and about half of the 23K are then returned to the stroma. Mutations in the twin-arginine motif block thylakoid targeting and maturation, confirming an involvement of the Tat apparatus. Mutation of the processing site yields membrane-associated intermediate-size protein in vivo, indicating a delayed reversal of translocation to the stroma and suggesting a longer lived interaction with the Tat machinery. We conclude that, in vivo, the Tat system can reject substrates at a late stage in translocation and on a very large scale, indicating the influence of factors that are absent in reconstitution assays.
|Item Type:||Journal Article|
|Subjects:||Q Science > QH Natural history > QH301 Biology|
|Journal or Publication Title:||JOURNAL OF CELL BIOLOGY|
|Publisher:||ROCKEFELLER UNIV PRESS|
|Date:||24 October 2005|
|Number of Pages:||9|
|Page Range:||pp. 281-289|
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